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Checking references for intended status: Informational ---------------------------------------------------------------------------- No issues found here. Summary: 1 error (**), 0 flaws (~~), 0 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group L. Han, Ed. 3 Internet-Draft R. Li 4 Intended status: Informational A. Retana 5 Expires: 7 September 2022 Futurewei Technologies, Inc. 6 M. Chen 7 China Mobile 8 N. Wang 9 University of Surrey 10 6 March 2022 12 Satellite Semantic Addressing for Satellite Constellation 13 draft-lhan-satellite-semantic-addressing-01 15 Abstract 17 This document presents a semantic addressing method for satellites in 18 satellite constellation connecting with Internet. The satellite 19 semantic address can indicate the relative position of satellites in 20 a constellation. The address can be used with traditional IP address 21 or MAC address or used independently for IP routing and switching. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at https://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on 7 September 2022. 40 Copyright Notice 42 Copyright (c) 2022 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 47 license-info) in effect on the date of publication of this document. 48 Please review these documents carefully, as they describe your rights 49 and restrictions with respect to this document. Code Components 50 extracted from this document must include Revised BSD License text as 51 described in Section 4.e of the Trust Legal Provisions and are 52 provided without warranty as described in the Revised BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 57 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 58 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4 59 4. Basics of Satellite Constellation and Satellite Orbit . . . . 5 60 4.1. Satellite Orbit . . . . . . . . . . . . . . . . . . . . . 5 61 4.2. Satellite Constellation Compositions . . . . . . . . . . 6 62 4.3. Communication between Satellites by ISL . . . . . . . . . 7 63 5. Addressing of Satellite . . . . . . . . . . . . . . . . . . . 9 64 5.1. Indexes of Satellite . . . . . . . . . . . . . . . . . . 9 65 5.2. The Range of Satellite Indexes . . . . . . . . . . . . . 12 66 5.3. Other Info for satellite addressing . . . . . . . . . . . 13 67 5.4. Encoding of Satellite Semantic Address . . . . . . . . . 14 68 5.5. Link Identification by Satellite Semantic Address . . . . 16 69 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 70 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 18 71 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18 72 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 73 9.1. Normative References . . . . . . . . . . . . . . . . . . 18 74 9.2. Informative References . . . . . . . . . . . . . . . . . 19 75 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 21 76 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21 78 1. Introduction 80 Satellite constellation technologies for Internet are emerging and 81 expected to provide Internet service like the traditional wired 82 network on the ground. A typical satellite constellation will have 83 couple of thousands or over ten thousand of LEO and/or VLEO. 84 Satellites in a constellation will be connected to adjacent 85 satellites by Inter-Satellite-Links (ISL), and/or connected to ground 86 station by microwave or laser links. ISL is still in research stage 87 and will be deployed soon. This memo is for the satellite networking 88 with the use of ISL. 90 The memo proposes to use some indexes to represent a satellite's 91 orbit information. The indexes can form satellite semantic address, 92 the address can then be embedded into IPv6 address or MAC address for 93 IP routing and switching. The address can also be used independently 94 if the shorter than 128-bit length of IP address is accepted. As an 95 internal address for satellite network, it only applies to satellites 96 that will form a constellation to transport Internet traffic between 97 ground stations and will not be populated to Internet by BGP. 99 2. Terminology 101 LEO Low Earth Orbit with the altitude from 180 km to 102 2000 km. 104 VLEO Very Low Earth Orbit with the altitude below 450 km 106 GEO Geosynchronous orbit with the altitude 35786 km 108 ISL Inter Satellite Link 110 ISLL Inter Satellite Laser Link 112 3D Three Dimensional 114 GS Ground Station, a device on ground connecting the 115 satellite. In the document, GS will hypothetically 116 provide L2 and/or L3 functionality in addition to 117 process/send/receive radio wave. It might be 118 different as the reality that the device to 119 process/send/receive radio wave and the device to 120 provide L2 and/or L3 functionality could be 121 separated. 123 SGS Source ground station. For a specified flow, a 124 ground station that will send data to a satellite 125 through its uplink. 127 DGS Destination ground station. For a specified flow, 128 a ground station that is connected to a local 129 network or Internet, it will receive data from a 130 satellite through its downlink and then forward to 131 a local network or Internet. 133 L1 Layer 1, or Physical Layer in OSI model [OSI-Model] 135 L2 Layer 2, or Data Link Layer in OSI model 136 [OSI-Model] 138 L3 Layer 3, or Network Layer in OSI model [OSI-Model], 139 it is also called IP layer in TCP/IP model 141 BGP Border Gateway Protocol [RFC4271] 143 IGP Interior gateway protocol, examples of IGPs include 144 Open Shortest Path First (OSPF [RFC2328]), Routing 145 Information Protocol (RIP [RFC2453]), Intermediate 146 System to Intermediate System (IS-IS [RFC7142]) and 147 Enhanced Interior Gateway Routing Protocol (EIGRP 148 [RFC7868]). 150 3. Overview 152 For IP based satellite networking, the topology is very dynamic and 153 the traditional IGP and BGP based routing technologies will face 154 challenges according to the analysis in 155 [I-D.lhan-problems-requirements-satellite-net]. From the paper, we 156 can easily categorize satellite links as two types, steady and un- 157 steady. For un-steady links, the link status will be flipping every 158 couple of minutes. 160 Section 5.5 has more details about how to identify different links. 162 Some researches have been done to handle such fast changed 163 topologies. one method to overcome the difficulties for routing with 164 un-steady links is to only use the steady links, and get rid of un- 165 steady links unless it is necessary. For example, for real 166 deployment, only links between satellite and ground stations are 167 mandatory to use, other un-steady links can be avoided in routing and 168 switching algorithms. [Routing-for-LEO] proposed to calculate the 169 shortest path by avoiding un-steady links in polar area and links 170 crossing Seam line since satellites will move in the opposite 171 direction crossing the Seam line. 173 Traditionally, to establish an IP network for satellites, each 174 satellite and its interface between satellites and to ground stations 175 have to be assigned IP addresses (IPv4 or IPv6). The IP address can 176 be either private or public. IP address itself does not mean 177 anything except routing prefix and interface identifier [RFC8200]. 179 To utilize the satellite relative position for routing, it is desired 180 that there is an easy way to identify the relative positions of 181 different satellites and identify un-steady links quickly. The 182 traditional IP address cannot provide such functionality unless we 183 have the real-time processing for 3D coordinates of satellites to 184 figure out the relative positions of each satellite, and some math 185 calculation and dynamic database are also needed in routing algorithm 186 to check if a link is steady or not. This will introduce extra data 187 exchanged for routing protocols and burden for the computation in 188 every satellite. Considering the ISL link speed (up to 10G for 189 2000km) and hardware cost (Radiation-hardened semiconductor 190 components are needed) in satellite are more constraint than for 191 network device on ground, it is expected to simplify the routing 192 algorithm, reduce the requirement of ISL, onboard CPU and memory. 194 The document proposes to form a semantic address by satellite orbit 195 information, and then embedded it into a proper IP address. The IP 196 address of IGP neighbors can directly tell the relative position of 197 different satellites and if links between two satellites are stead or 198 not. 200 The document does not describe the details how the semantic address 201 is used to improve routing and switching or new routing protocols, 202 those will be addressed in different documents. 204 4. Basics of Satellite Constellation and Satellite Orbit 206 This section will introduce some basics for satellite such as orbit 207 parameters. 209 4.1. Satellite Orbit 211 The orbit of a satellite can be either circular or ecliptic, it can 212 be described by following Keplerian elements [KeplerianElement]: 214 1. Inclination (i) 216 2. Longitude of the ascending node (Omega) 218 3. Eccentricity (e) 220 4. Semimajor axis (a) 222 5. Argument of periapsis (omega) 224 6. True anomaly (nu) 226 The circular orbit is widely used by proposals of satellite 227 constellation from different companies and countries. 229 For a circular orbit, we will have: 231 * Eccentricity e = 0 233 * Semimajor axis a = Altitude of satellite 234 * Argument of periapsis omega = 90 degree 236 So, three parameters, Altitude, Inclination and Longitude of the 237 ascending node, will be enough to describe the orbit. The satellite 238 will move in a constant speed and True anomaly (nu) can be easily 239 calculated after the epoch time is defined. 241 4.2. Satellite Constellation Compositions 243 One satellite constellation may be composed of many satellites (LEO 244 and VLEO), but normally all satellites are grouped in a certain order 245 that is never changed during the life of satellite constellation. 246 Each satellite constellation's orbits parameters described in 247 Section 4.1 must be approved by regulator and cannot be changed 248 either. Follows are characters of one satellite constellation: 250 1. One Satellite Constellation is composed of couple of shell groups 251 of satellites. 253 2. Same shell group of satellite will have the same altitude and 254 inclination. 256 3. The total N orbit planes in the same shell group of satellites 257 will be evenly distributed by the same interval of Longitude of 258 the ascending node (Omega). The interval equals to (360 degree/ 259 N). As a result, all orbit planes in the same shell group will 260 effectively form a shell to cover earth (there will be a coverage 261 hole for the shell if the inclination angle is less than 90 262 degree). 264 4. Each orbit plane in the same shell group will have the same 265 number of satellites, all satellites in the same orbit plane will 266 be evenly distributed angularly in the orbit plane. 268 5. All satellites in the same shell group are moving in the same 269 circular direction within the same orbit plane. As a result, at 270 any location on earth, we can see there will have two group of 271 satellites moving on the opposite direction. One group moves 272 from south to north, and another group moves from north to south. 273 Section 5.5 has more details. 275 4.3. Communication between Satellites by ISL 277 When ISL is used for the communication between satellites, each 278 satellite will have a fixed number of links to connect to its 279 neighbor. Due to the cost of ISL and the constraints of power supply 280 on satellite, the number of ISL is normally limited to connect to its 281 closest neighbors. In 3D space, each satellite may have six types of 282 adjacent satellites, each type represents one direction. The number 283 of adjacent neighbors in one direction is dependent on the number of 284 deployment of ISL device on satellites, for example, the laser 285 transmitter and receiver for ISLL. Figure 1 illustrates satellite S0 286 and its adjacent neighbors. 288 / / / 289 / / / 290 / / / 291 S7 S8 S9 292 / / / 293 / / / 294 / / / 295 / S1 / 296 S5 / S3 297 / / / 298 / S0 / 299 / / / 300 S6 / S4 301 / S2 / 302 / / / 303 / / / 304 / / / 305 S10 S11 S12 306 / / / ^ Moving direction 307 / / / / 308 / / / / 309 orbit orbit orbit 311 Figure 1: Satellite S0 and its adjacent neighbors 313 All adjacent satellites of S0 in Figure 1 are listed below: 315 1. The front adjacent satellite S1 that is on the same orbit plane 316 as S0. 318 2. The back adjacent satellite S2 that is on the same orbit plane as 319 S0 321 3. The right adjacent satellites S3 and S4 that are on the right 322 orbit plane of S0 324 4. The left adjacent satellites S5 and S6 that are on the left orbit 325 plane of S0 327 5. The above adjacent satellites S7 to S9 that are on the above 328 orbit plane of S0 330 6. The below adjacent satellite S10 to S12 that are on the below 331 orbit of plane S0 333 The relative position of adjacent satellites will directly determine 334 the quality of ISL and communication. From the analysis in 335 [I-D.lhan-problems-requirements-satellite-net], The speed of 336 satellite is only related to the altitude of the satellite (on 337 circular orbit), all satellites with a same altitude will move with 338 the same speed. So, in above adjacent satellites, some adjacent 339 satellite's relative positions are steady and the ISL can be alive 340 without interruption caused by movement. Some adjacent satellites 341 relative positions are changing quickly, the ISL may be down since 342 the distance may become out of reach for the laser of ISL, or the 343 quick changed positions of two satellite make the tracking of laser 344 too hard. Below are details: 346 * The relative position of satellites in the same orbit plane will 347 be the steadiest. 349 * The relative position of satellites in the direct neighbor orbit 350 planes in the same shell group and moving in the same direction 351 will be steady at equator area, but will be changing when two 352 orbits meet on the polar area. Whether the link status will be 353 flipping depends on the tracking technology and the range of laser 354 pointing angle of ISL. See Figure 2. 356 * The relative position of satellites in the neighbor orbit planes 357 in the same shell group but moving in the different direction will 358 not be steady at all times. More details are explained in 359 Figure 8 361 * The relative position of satellites in the neighbor orbit planes 362 in the different shell group will be dependent on the difference 363 of altitude and inclination. This has been analyzed in 364 [I-D.lhan-problems-requirements-satellite-net]. 366 \ / 367 P3 P4 368 \ / 369 \/ 370 /\ 371 / \ 372 P1 P2 373 / \ 375 * Two satellites S1 and S2 are at position P1 and P2 at time T1 376 * S1's right facing ISL connected to S2's left facing ISL 377 * S1 and S2 move to the position P4 and P3 at time T2 378 * S1's left facing ISL connected to S2's right facing ISL 379 * So, if the range of laser pointing angle is 360 degree and 380 tracking technology supports, the ISL will not be flipping 381 after passing polar area; Otherwise, the link will be flipping 383 Figure 2: Satellite's Position and ISL Change at Polar Area 385 5. Addressing of Satellite 387 When ISL is deployed in satellite constellation, all satellites in 388 the constellation can form a network like the wired network on 389 ground. Due to the big number of satellites in a constellation, the 390 network could be either L2 or L3. The document proposes to use L3 391 network for better scalability. 393 When satellites form a L3 network, it is expected that IP address is 394 needed for each satellite and its ISLs. 396 While the traditional IP address can still be used for satellite 397 network, the document proposes an alternative new method for 398 satellite's addressing system. The new addressing system can 399 indicate a satellite's orbit info such as shell group index, orbit 400 plane index and satellite index. This will make the adjacent 401 satellite identification for link status easier and benefit the 402 routing algorithms. 404 5.1. Indexes of Satellite 406 As described in Section 4.2, one satellite has three important orbit 407 related information as described below. 409 1. Index for the shell group of satellites in a satellite 410 constellation 412 2. Index for the orbit plane in a shell group of satellites 413 3. Index for the satellite in an orbit plane 415 It should be noted that for all type of indexes, it is up to the 416 owner to assign the index number. There is no rule for which one 417 should be assigned with which number. The only important rule is 418 that all index number should be in sequential to reflect its relative 419 order and position with others. Below is an example of assignment 420 rules: 422 1. The 1st satellite launched in an orbit plane can be assigned for 423 the 1st satellite index (0), the incremental direction of the 424 satellite index in the same orbit plane is the incremental 425 direction of "Argument of periapsis (omega)" 427 2. The 1st orbit plane established can be assigned for the 1st orbit 428 plane index (0), the incremental direction of the orbit plane 429 index is the incremental direction of "Longitude of the ascending 430 node (Omega)". 432 3. The shell group of satellites with the lowest altitude can be 433 assigned for the 1st shell group index (0), the incremental 434 direction of shell group index is the incremental direction of 435 altitude. 437 Figure 3 and Figure 4 illustrate three types of indexes for 438 satellite. 440 / / / \ 441 / / / | 442 / / / | 443 S S S > shell group3 444 / / / | 445 / / / | 446 / / / / 447 / S / \ 448 S / S | 449 / / / | 450 / S / > shell group2 451 / / / | 452 S / S | 453 / S / / 454 / / / \ 455 / / / | 456 / / / | 457 S S S > shell group1 458 / / / | 459 / / / | 460 / / / / 461 orbit orbit orbit ----> Earth self-rotation 462 plane1 plane2 plane3 464 Figure 3: Shell Group and Orbit Plane Indexes for Satellites 466 Shell Group and Orbit Plane Indexes for Satellites 468 , - ~ S1 ~ - , 469 S2 ' ' S8 470 , , 471 , , 472 , , Indexed 473 S3 S7 <-- satellite 474 , , in one orbit plane 475 , , 476 , , ^ move direction 477 S4 , S6 / 478 ' - , _ S5_ , ' / 480 Figure 4 482 Three type of Index for satellites 484 5.2. The Range of Satellite Indexes 486 The ranges of different satellite indexes will determine the range 487 the dedicated field for semantic address. The maximum indexes depend 488 on the number of shell group, orbit plane and satellite per orbit 489 plane. The number of orbit plane and satellite per orbit plane have 490 relationship with the coverage of a satellite constellation. There 491 are minimum numbers required to cover earth. 492 [I-D.lhan-problems-requirements-satellite-net] has given the detailed 493 math to estimate the minimal number required to cover the earth. 494 There are two key parameters that determine the minimal number of 495 satellite required. One is the elevation angle, another is the 496 altitude. SpaceLink has proposed two elevation angles, 25 and 35 497 degrees [SpaceX-Non-GEO]. The lowest LEO altitude can be 160km 498 according to [Lowest-LEO-ESA]. The Table 1 and Table 2 illustrate 499 the estimation for different altitude (As), the coverage radius (Rc), 500 the minimal required number of orbit planes (No) and satellite per 501 orbit plane (Ns). The elevation angle is 25 degree and 35 degrees 502 respectively. 504 +============+=======+=======+======+======+======+======+======+ 505 | Parameters | VLEO1 | VLEO2 | LEO1 | LEO2 | LEO3 | LEO4 | LEO5 | 506 +============+=======+=======+======+======+======+======+======+ 507 | As(km) | 160 | 300 | 600 | 900 | 1200 | 1500 | 2000 | 508 +------------+-------+-------+------+------+------+------+------+ 509 | Rc(km) | 318 | 562 | 1009 | 1382 | 1702 | 1981 | 2379 | 510 +------------+-------+-------+------+------+------+------+------+ 511 | Ns | 73 | 42 | 23 | 17 | 14 | 12 | 10 | 512 +------------+-------+-------+------+------+------+------+------+ 513 | No | 85 | 48 | 27 | 20 | 16 | 14 | 12 | 514 +------------+-------+-------+------+------+------+------+------+ 516 Table 1: Satellite coverage (Rc), minimal number of orbit 517 plane (No) and satellite (Ns) per orbit plane for different 518 LEO/VLEOs, Elevation angle = 25 degree 520 +============+=======+=======+======+======+======+======+======+ 521 | Parameters | VLEO1 | VLEO2 | LEO1 | LEO2 | LEO3 | LEO4 | LEO5 | 522 +============+=======+=======+======+======+======+======+======+ 523 | As(km) | 160 | 300 | 600 | 900 | 1200 | 1500 | 2000 | 524 +------------+-------+-------+------+------+------+------+------+ 525 | Rc(km) | 218 | 392 | 726 | 1015 | 1271 | 1498 | 1828 | 526 +------------+-------+-------+------+------+------+------+------+ 527 | Ns | 107 | 59 | 32 | 23 | 19 | 16 | 13 | 528 +------------+-------+-------+------+------+------+------+------+ 529 | No | 123 | 69 | 37 | 27 | 22 | 18 | 15 | 530 +------------+-------+-------+------+------+------+------+------+ 532 Table 2: Satellite coverage (Rc), minimal number of orbit 533 plane (No) and satellite (Ns) per orbit for different LEO/ 534 VLEOs, Elevation angle = 35 degree 536 The real deployment may be different as above analysis. Normally, 537 more satellites and orbit planes are used to provide better coverage. 538 So far, there are only two proposals available, one is StarLink, 539 another is from China Constellation. For proposals of [StarLink], 540 there are 7 shell groups, the number of orbit plane and satellites 541 per orbit plane in all shell groups are 72 and 58; For proposals of 542 [China-constellation], there are 7 shell groups, the number of orbit 543 plane and satellites per orbit plane in all shell groups are 60 and 544 60; 546 It should be noted that some technical parameters, such as the 547 inclination and altitude of orbit planes, in above proposals may be 548 changed during the long-time deployment period, but the total numbers 549 for indexes normally do not change. 551 From the above analysis, to be conservative, it is safe to conclude 552 that the range of all three satellite indexes are less than 256, or 553 8-bit number. 555 5.3. Other Info for satellite addressing 557 In addition to three satellite indexes described in Section 5.1, 558 other information is also important and can also be embedded into 559 satellite address: 561 1. The company or country code, or the owner code. In the future, 562 there may have multiple satellite constellations on the sky from 563 different organizations, and the inter-constellation 564 communication may become as normal that is similar to the network 565 on the ground. This code will be useful to distinguish different 566 satellite constellation and make the inter-constellation 567 communication possible. One satellite constellation will have 568 one code assigned by international regulator (IANA or ITU). 569 Considering the limit of LEO orbits and the cost of satellite 570 constellations, the total number of satellite constellation is 571 very limited. So, the size of code is limited. 573 2. The Interface Index. This index is to identify the ISL or ISLL 574 for a satellite. As described in Section 4.3, the total number 575 of ISL is limited. So, the size of interface index is also 576 limited. 578 5.4. Encoding of Satellite Semantic Address 580 The encoding for satellite semantic address is dependent on what 581 routing and switching (L2 or L3 solution) technologies are used for 582 satellite networking, and finally dependent on the decision of IETF 583 community. 585 Follows are some initial proposals: 587 1. When satellite network is using L3 solution, the satellite 588 semantic address is encoded as the interface identifier (i.e., 589 the rightmost 64 bits) of the IPv6 address for IPv6. Figure 5 590 shows the format of IPv6 Satellite Address. 592 2. When satellite network is using L2 solution, the satellite 593 semantic address can be embedded into the field of "Network 594 Interface Controller (NIC) Specific" in MAC address 595 [IEEE-MAC-Address]. But due to shorter space for NIC, the "Index 596 for the shell group" and "Index for Interface" will only have 597 4-bit. This is illustrated in Figure 6. This encoded MAC 598 address can also be used for L3 solution where the interface MAC 599 may be also needed to be configured for each ISL. 601 3. Recently, some works suggested to use Length Variable IP address 602 for routing and switching [Length-Variable-IP] or use flexible IP 603 address [I-D.jia-flex-ip-address-structure] or shorter IP address 604 [I-D.li-native-short-addresses] to solve some specific problems 605 that regular IPv6 is not very suitable. Satellite network also 606 belongs to such specific network. Due to the resource and cost 607 constraints and requirement for radiation hardened electronic 608 components, the ISL speed, on-board processor and memory are 609 limited in performance, power consumption and capacity compared 610 with network devices on ground. So, using IPv6 directly in 611 satellite network is not an optimal solution because IPv6 header 612 size is too long for such small network. From above analysis, 613 32-bit to 64-bit length of IP address is enough for satellite 614 networking. Using 128-bit IPv6 will consume more resource 615 especially the ISL bandwidth, processing power and memory, etc. 617 If shorter than 128-bit IP address is accepted as IETF work, the 618 satellite semantic address can be categorized as a similar use 619 case. Figure 7 illustrates a 32-bit Semantic Satellite Address 620 format. The final coding for the shorter IP address can be 621 decided by the community. How to use the 32-bit Semantic 622 Satellite address can be addressed later on in different 623 document. 625 0 1 2 3 626 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 627 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 628 ~ Subnet Prefix (64 bits) ~ 629 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 630 | Owner Code | Shell_Index | Orbit_Index | Sat_Index | 631 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 632 | Intf_Index | Reserved | 633 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 635 Owner Code: Identifier for the owner of the constellation 636 Shell_Index: Index for the shell group of satellite in a satellite 637 constellation 638 Orbit_Index: Index for the orbit plane in a shell group of satellite 639 Sat_Index: Index for the satellite in an orbit plane 640 Intf_Index: Index for interface on a satellite 641 Reserved: 24-bits reserved 643 Figure 5: The IPv6 Satellite Address 645 3 Octets 3 Octets 646 /---------^--------\ /--------^--------\ 647 +-------------------+-------------------+ 648 | OUI | Sat Address | 649 +-------------------+-------------------+ 650 | 651 | 652 +-------------------------------+ 653 | 654 | 655 v 657 0 1 2 3 658 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 659 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 660 | Shell | Orbit_Index | Sat_Index |Intf_Id| 661 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 663 OUI: Organizationally Unique Identifier assigned by IEEE 664 Shell: 4-bit Index for the shell group of satellite in a satellite 665 constellation 666 Orbit_Index: Index for the orbit plane in the group of satellite 667 Sat_Index: Index for the satellite in the orbit plane 668 Intf_Id: 4-bit Index for interface on a satellite 670 Figure 6: The MAC Satellite Address 672 0 1 2 3 673 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 674 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 675 | Owner Code | Shell_Index | Orbit_Index | Sat_Index | 676 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 678 Owner Code: Identifier for the owner of the constellation 679 Shell_Index: Index for the shell group of satellite in a satellite 680 constellation 681 Orbit_Index: Index for the orbit plane in a shell group of satellite 682 Sat_Index: Index for the satellite in an orbit plane 684 Figure 7: The 32-bit Semantic Satellite Address 686 5.5. Link Identification by Satellite Semantic Address 688 Using above satellite semantic addressing scheme, to identify steady 689 and un-steady links is as simple as below: 691 Assuming: 693 1. The total number of satellites per orbit plane is M 695 2. The total number of orbit planes per shell group is N. 697 3. Two satellites have: 699 * Satellite Indexes as: Sat1_Index, Sat2_Index 701 * Orbit plane Indexes as: Orbit1_Index, Orbit2_Index 703 * Shell group Indexes as: Shell1_Index, Shell2_Index 705 Steady links: 707 1. The links between adjacent satellites on the same orbit plane, 708 or, the satellite indexes satisfy: 710 * Sat2_Index = Sat1_Index + 1, when Sat1_Index < M-1; Sat2_Index 711 = 0, when Sat1_Index = M-1; and 713 * Orbit1_Index = Orbit2_Index, Shell1_Index = Shell2_Index. 715 2. The links between satellites on adjacent orbit planes on the same 716 altitude. and two satellites are moving to the same direction, 717 or, the satellite indexes satisfy: 719 * Orbit2_Index = Orbit1_Index + 1, when Orbit1_Index < N-1; 720 Orbit2_Index = 0, when Orbit1_Index = N-1; and 722 * Shell1_Index = Shell2_Index. 724 * Sat1_Index and Sat2_Index may be equal or have difference, 725 depend on how the link is established. 727 Un-Steady links: 729 1. The links between satellite and ground stations. 731 2. The links between satellites on adjacent orbit planes on the same 732 altitude. Two satellites are moving to the different direction. 733 Or, the satellite indexes do not satisfy conditions described in 734 above #2 for Steady links. 736 3. The links between satellites on adjacent orbit planes on 737 different altitude. Or, the satellite indexes satisfy: 739 * Shell1_Index != Shell2_Index. 741 Figure 8 illustrates the links for adjacent orbit planes (#2 for 742 Steady Link and Un-steady Link above). From the figure, it can be 743 noticed that some links may have shorter distance than steady link, 744 but they are unsteady. For example, the links between S1 and S4; S4 745 and S2; S2 and S5, etc. 747 i+N/2 i+1+N/2 i+2+N/2 748 / \ / \ / \ 749 / \ / \ / \ 750 S1............S2............S3 \ 751 / S4 ..........S5............S6 752 / \ / \ / \ 753 / \ / \ / \ 754 i-1 i i+1 756 * The total number of orbit planes are N 757 * The number (i-1, i, i+1,...) represents the Orbit index 758 * The bottom numbers (i-1, i, i+1) are for orbit planes on 759 which satellites (S1, S2, S3) are moving from bottom to up. 760 * The top numbers (i+N/2, i+1+N/2, i+2+N/2) are for orbit 761 planes on which satellites (S4, S5, S6) are moving from up 762 to bottom. 763 * Dot lines are the steady links 765 Figure 8: The links between satellites on adjacent orbit planes 767 6. IANA Considerations 769 This memo may include request to IANA for owner code, see 770 Section 5.4. 772 7. Contributors 774 8. Acknowledgements 776 9. References 778 9.1. Normative References 780 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 781 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 782 DOI 10.17487/RFC4271, January 2006, 783 . 785 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 786 DOI 10.17487/RFC2328, April 1998, 787 . 789 [RFC7142] Shand, M. and L. Ginsberg, "Reclassification of RFC 1142 790 to Historic", RFC 7142, DOI 10.17487/RFC7142, February 791 2014, . 793 [RFC2453] Malkin, G., "RIP Version 2", STD 56, RFC 2453, 794 DOI 10.17487/RFC2453, November 1998, 795 . 797 [RFC7868] Savage, D., Ng, J., Moore, S., Slice, D., Paluch, P., and 798 R. White, "Cisco's Enhanced Interior Gateway Routing 799 Protocol (EIGRP)", RFC 7868, DOI 10.17487/RFC7868, May 800 2016, . 802 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 803 (IPv6) Specification", STD 86, RFC 8200, 804 DOI 10.17487/RFC8200, July 2017, 805 . 807 9.2. Informative References 809 [I-D.lhan-problems-requirements-satellite-net] 810 Han, L., Li, R., Retana, A., Chen, M., Su, L., and N. 811 Wang, "Problems and Requirements of Satellite 812 Constellation for Internet", Work in Progress, Internet- 813 Draft, draft-lhan-problems-requirements-satellite-net-02, 814 13 February 2022, . 817 [I-D.jia-flex-ip-address-structure] 818 Jia, Y., Chen, Z., and S. Jiang, "Flexible IP: An 819 Adaptable IP Address Structure", Work in Progress, 820 Internet-Draft, draft-jia-flex-ip-address-structure-00, 31 821 October 2020, . 824 [I-D.li-native-short-addresses] 825 Li, G., Jiang, S., and D. E. 3rd, "Native Short Addresses 826 for the Internet Edge", Work in Progress, Internet-Draft, 827 draft-li-native-short-addresses-01, 25 May 2021, 828 . 831 [Routing-for-LEO] 832 E. Ekici, I. F. Akyildiz and M. D. Bender, ""Datagram 833 routing algorithm for LEO satellite networks," Proceedings 834 IEEE INFOCOM 2000. Conference on Computer Communications. 835 Nineteenth Annual Joint Conference of the IEEE Computer 836 and Communications Societies (Cat. No.00CH37064), 2000, 837 pp. 500-508 vol.2, doi: 10.1109/INFCOM.2000.832223.", 838 . 840 [Length-Variable-IP] 841 Shoushou Ren, Delei Yu, Guangpeng Li, Shihui Hu, Ye Tian, 842 Xiangyang Gong, Robert Moskowitz, ""Routing and Addressing 843 with Length Variable IP Address," NEAT'19: Proceedings of 844 the ACM SIGCOMM 2019 Workshop on Networking for Emerging 845 Applications and Technologies, August 2019", 846 . 848 [IEEE-MAC-Address] 849 "IEEE Std 802-2001 (PDF). The Institute of Electrical and 850 Electronics Engineers, Inc. (IEEE). 2002-02-07. p. 19. 851 ISBN 978-0-7381-2941-9. Retrieved 2011-09-08.", 852 . 855 [Lowest-LEO-ESA] 856 "Lowest LEO by ESA", 857 . 861 [KeplerianElement] 862 "Keplerian elements", 863 . 865 [OSI-Model] 866 "OSI Model", . 868 [StarLink] "Star Link", . 870 [China-constellation] 871 "China Constellation", . 874 [SpaceX-Non-GEO] 875 "FCC report: SPACEX V-BAND NON-GEOSTATIONARY SATELLITE 876 SYSTEM", . 879 Appendix A. Change Log 881 * Initial version, 10/19/2021 883 * 01 version, 02/28/2022 885 Authors' Addresses 887 Lin Han (editor) 888 Futurewei Technologies, Inc. 889 2330 Central Express Way 890 Santa Clara, CA 95050, 891 United States of America 892 Email: lhan@futurewei.com 894 Richard Li 895 Futurewei Technologies, Inc. 896 2330 Central Express Way 897 Santa Clara, CA 95050, 898 United States of America 899 Email: rli@futurewei.com 901 Alvaro Retana 902 Futurewei Technologies, Inc. 903 2330 Central Express Way 904 Santa Clara, CA 95050, 905 United States of America 906 Email: alvaro.retana@futurewei.com 908 Meiling Chen 909 China Mobile 910 32, Xuanwumen West 911 BeiJing 100053 912 China 913 Email: chenmeiling@chinamobile.com 915 Ning Wang 916 University of Surrey 917 Guildford 918 Surrey, GU2 7XH 919 United Kingdom 920 Email: n.wang@surrey.ac.uk